New Delhi: The south-west monsoon, a lifeline for many regions in India, arrived in Kerala on Thursday, June 4. The India Meteorological Department (IMD) has forecast heavy to very heavy rains in several states in south India for the next seven days.Per the met department, heatwave conditions have decreased since May 31 thanks to a meteorological phenomenon called a western disturbance. Monsoonal rains over Kerala, KarnatakaThe IMD announced in a press release on Thursday that over the next week, isolated heavy to very heavy rainfall (ranging from 7-20cm) is very likely over Kerala and Karnataka, while Tamil Nadu will receive isolated heavy rainfall. Heavy to very heavy rainfall is likely to continue over northeast India for the next 5-6 days. The monsoon usually hits the southern state of Kerala on June 1, but IMD officials had said in a press conference on May 29 that a range of seven days is still acceptable. So the monsoon has not been delayed. However, the officials did predict a below-normal monsoon this year.Per the IMD on June 4, the southwest monsoon has advanced into most parts of the Arabian Sea, all over the Lakshadweep islands, Kerala and Mahe, some parts of Karnataka, Tamil Nadu and other parts of the Comorin area, and most parts of the Bay of Bengal on Thursday.A commuter rides a two wheeler through rains, in Thiruvananthapuram, Kerala, Thursday, June 4, 2026. Photo: PTI“Conditions are favourable for further advance of southwest monsoon into some more parts of central Arabian Sea, entire Goa, some parts of Maharashtra and Andhra Pradesh, some more parts of Karnataka, remaining parts of Tamil Nadu, Southwest Bay of Bengal, some more parts of Westcentral, Eastcentral and Northeast Bay of Bengal, some parts of Northeastern state during next 2-3 days,” the IMD said.The met department also issued warnings for fishermen to not venture into many parts of both the Bay of Bengal and Arabian Sea between today and June 9.Heatwaves to decreaseMeanwhile, some parts of north India could continue witness heat wave conditions. These include isolated pockets of Bihar (from June 6-8), eastern Uttar Pradesh (from June 7-10), western Uttar Pradesh (June 8-10). Hot and humid weather conditions, meanwhile, are likely to continue over Odisha (June 4-8), and during June 4 and 5 in coastal Andhra Pradesh and Yanam, Nagaland, Manipur, Mizoram, Tripura, Tamil Nadu, Puducherry and Karaikal.Women cover themselves amid rainfall as the southwest monsoon set over Kerala according to the India Meteorological Department (IMD), in Kochi. Photo: PTI“Last week’s heat wave spell abated from the country since 31st May due to large-scale thunderstorm activity in association of an active Western Disturbance,” the IMD announced in another press release on June 4.Western disturbances are a meteorological phenomenon; they are extratropical cyclones (low-press systems often associated with heavy precipitation and strong winds) that originate in the mid-latitudes. They play a crucial role in bringing both rainfall and snow into the Indian subcontinent.Excess rainfall in March-MayAn angler stands on a broken bridge after the southwest monsoon sets over Kerala. Photo: PTIThe IMD’s maps published on June 4 also reveal that many parts of India witnessed ‘excess’ rainfall, defined by an excess of 20-59%, and ‘large excess’ rainfall – 60% or more than normal – from March and May this year. These include parts of north and northwest India including Saurashtra, Bihar, eastern and western Uttar Pradesh, eastern Rajasthan and western Madhya Pradesh. Other areas that received such rainfall include Odisha, Jharkhand, and north interior Karnataka.However, Marathwada, coastal Andhra Pradesh and Yanam, Telangana and parts of interior Maharashtra, Arunachal Pradesh, Jammu and Kashmir and the Andaman and Nicobar islands witnessed deficit rainfall.